In the discussion of the background that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art.
Horizontal shaft impact crushers are utilized in many applications for crushing hard material, such as pieces of rock, ore etc. A horizontal shaft impact crusher has an impeller that is made to rotate around a horizontal axis. Pieces of rock are fed towards the impeller and are struck by beater elements mounted on the impeller. The pieces of rock are disintegrated by being struck by the beater elements, and are accelerated and thrown against breaker plates, often referred to as curtains, against which further disintegration occurs. The action of the impeller thus causes the material fed to the horizontal shaft impact crusher to move freely in a crushing chamber and to be crushed upon impact against the beater elements, against the curtains, and against other pieces of material moving around at high speed in the crushing chamber.
Adjustment of the position of the curtain may be made to compensate for both curtain wear and beater element wear. Furthermore, adjustment of the position of the curtain can be made to adjust the size of the crushed material.
U.S. Pat. No. 4,017,035 discloses a horizontal shaft impact crusher which is provided with supporting hydraulic cylinders for adjusting and maintaining the position of the curtain.
However, the design of the crusher described in U.S. Pat. No. 4,017,035 is considered to be relatively complex and costly to manufacture and/or operate.